The present invention relates to incandescent lamps, and more particularly, to an incandescent lamp suitably used as a lamp for projection and as a lamp for recording and reproduction.
In incandescent lamps of the type described, for example, an incandescent lamp for projection used for a projector, it is necessary to position with high accuracy a filament as a light source onto a lens axis of a condensing optical system and a projecting optical system. Also, in a lamp for recording and reproduction, for example, used for optical recording and optical reproduction when a talking picture is taken or projected, it is necessary to position with high accuracy a filament as a light source to a film in order to realize an acoustic effect as expected.
In the past, a proposal has been made to locate a filament of the lamp with high accuracy in connection with an external optical system. In this proposal, the relation between the filament and a base for fixedly holding the filament is not settled due to the difficulty in assembling elements with high accuracy when the lamp is produced. Thus, in this conventional arrangement, a fixing member is disposed externally of the base of the lamp, and the lamp is actually lighted so that the fixing position of the fixing member to the base is adjusted and thereafter both elements are fixed such as by soldering. However, such adjustment and fixation of the fixing member require labor and and is cumbersome.
It is therefore an object of the present invention to provide an incandescent lamp which can accurately position the distance between a reference position of a base and a filament.
It is a further object of the present invention to provide an incandescent lamp which can be produced simply without requiring a complicated process of manufacture.